Improvement in trunk-engines



UNITED STATES IMPROVEMENT IN PATENT OFFICE.`

THOMAS NORTHEY, OF ST. ll/IAYBEW PARISH, ENGLAND.

TRUNK-ENGINES.

Specification forming part of Letters Patent No.` 37,302, dated January (i, 1863.

To a/ZZ whom it may concern:

Be it known that l, THoMAs NoRTHEY, of the parish of St. Maybew, in the county of Gownwall, in the United Kingdom of Great Britain and Ireland, temporarily residing in the city of Hamilton, in the Province of Ganada, have invented a new and useful Improvement in Steam-Engines; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming a part of this specification, in which Figure 1 is a central vertical section of an engine with my improvement. Figs. 2` and 3 are vertical sections of the valve and seat on a larger scale than and in diii'erent positions from Fig. l.

Similar letters of reference indicate corresponding parts in both figures.

This invention relates to that class of steamengines known as truuk-engines 7; and it consists in so constructing, applying, and operating the induction and eduction valve of such an engine as to cause the admission of steam from the boiler to the cylinder on that side of the piston on which the trunk is situated, and which presents but a comparatively small area in annular form, and to cause the steam, after it has produced a stroke of the piston by its action on that side, to pass to the opposite side, and produce the return-stroke by the action of its expansive force on the larger area of the latter side, by which means, the areas ofthe two sides of the piston being properly proportioned, I am enabled to`obtain a nearly uniform development of power during both strokes, or during the complete revolution of the shaft.

To enable those skilled in the art tomake and use my invention, I will proceed to describe its construction and operation.

A is the framing of the engine.

B is the cylinder, arranged in an upright position on the top of the framing; and C is the crank-shaft'arranged below the cylinder.

D is the trunk, working through a stuffingbox, b, in the lower cylinder-head, c, and having its upper part enlarged to form the head of the piston E.

F is the connecting-rod, connecting the piston with the crank-wrist a. This rod is attached to the piston by a pin, d, inserted through the piston-head.

G is the valve-chest, and H the slide-valve, serving both for induction and eduction, operated by an eccentric-wrist, f, carried by the crank-shaft, in the same manner as the slidevalve of an ordinary reciprocating engine.

The arrangement in the valve-seat ofthe steam-ports s s', communicating with opposite ends of the cylinder, and of the exhaust-port e, communicating with the atmosphere or with a condenser, is substantially like the arrangement of such ports in an ordinary reciprocating engine having only one slide-valve for induction and eduction. The slide-valve, besides having an exhaust-cavity, g, like that in an ordinary slide valve, has a passage, h, passing round the back ofthe said cavity and terminating in the face of the valve in two ports, t i', oneon each side of the cavity g, said ports being at such distance apart as to be capable of forming communication between the two ports s s', as shown in Fig. 2. The valve is so set and has such a length of stroke as to make it uncover the lower cylinder-port, s',

when at the extreme upper end of its stroke, as shown in Fig. 8, in which position the upper port, s, is open to the exhaust-port e.

Fig. l represents the valve at about the middle of its upward stroke, t-he piston having just commenced its upward stroke, the lower port, s, just opening to the valve-chest, and the upper one, s', opening to the exhaust-port e. The upper port, i, is never open to the valve-chest, as it only receives steam from the lower part of the cylinder through the passage h. When thepiston has arrived atits lowest position the valve, commencing to open the port s', admits steam from the boiler to the lower end of the cylinder, to act on the small areas of piston-surface surrounding the trunk, and thereby produce the upward stroke of the piston. This admission of steam may be continued throughout the whole upward stroke; or, by making the valve with proper lap, it may be caused to cut ofi' the steam before the stroke is completed, and its completion may be effected by the expansion of the steam. When the piston has arrived in its highest position,

the port t" ofthe valve, beginning to open to the port s', which is now closedto the valvechest, allows the steam to escape from the portion of the cylinder below into the p0rtion of the cylinder above the piston, where it expands, and, owing to the larger area of the upper side of the piston, forces the latter downward, the ports i' and s remaining in communication until the downward stroke of the piston has been completed, when the port s is closed bythe upward movement of the vllve, which instantly afterward opens the .port s to the valve-chest to admit steam from the boiler to the cylinder below the piston. In case of the engine having been stopped while the port s was closed to the valvechest--tliat is to say, during,` the downward stroke of the piston-it will be necessary, in order to start it, to admit steam direct from the boilerto the upper end of the cylinder to act upon the piston. To provide for this there is a passage, j, leading` directly from the valvechest to that end of the cylinder, such passage being furnished with a stop-cock, to be opened when the engine is to be started and THOMAS NORTHEY.

Witnesses:

W. W. HUNDLEY, GHAs. H. DAvIs. 

